Both opinions are notable as strongly textualist, though. In Schein, the question presented was

Whether the Federal Arbitration Act permits a court to decline to enforce an agreement delegating questions of arbitrability to an arbitrator if the court concludes the claim of arbitrability is “wholly groundless.”

The Court concluded:

The question presented in this case is whether the “wholly groundless” exception is consistent with the Federal Arbitration Act. We conclude that it is not. The Act does not contain a “wholly groundless” exception, and we are not at liberty to rewrite the statute passed by Congress and signed by the President.

Note here that there's a good pragmatic argument for the "wholly groundless" rule. Why constitute an arbitration tribunal just for the purpose of assessing a claim that is "wholly groundless"? Why not give federal courts the power to avert this obvious waste of time and resources? Answer: because the statute doesn't grant this power.

In Culberson, the question presented was:

Whether fees [for representation of claimants under the Social Security Act] subject to § 406(b)’s 25-percent cap include ... only fees for representation in court or ... also [include] fees for representation before the [Social Security Administration].

Again, it seems reasonable to say that the 25% cap applies across the board. Why cap fees for representation in court but not cap fees for representation before the agency? Answer: because that's what the statute says. As Justice Thomas wrote for the Court:

Because §406(b) by its terms imposes a 25% cap on fees only for representation before a court, and §406(a) has separate caps on fees for representation before the agency, we hold that the statute does not impose a 25% cap on aggregate fees.

I think both cases are emblematic of a decisive shift in the legal culture. Both cases reject pragmatic doctrines developed by the courts of appeal decades ago. I doubt that either would have come out the same way at the Supreme Court forty years earlier, and at least they surely would not have been unanimous. The short of it is that, in cases that are not politically charged, if the text is clear, it will be applied, even if there is a good pragmatic argument on the other side. From a rule of law perspective, that's progress.